Method and apparatus at a draw frame for fibre slivers, for adjusting the nip line spacing of a drawing mechanism

ABSTRACT

In a method, at a draw frame for fibre slivers, of adjusting the nip line spacing of a drawing mechanism, which has at least two drawing mechanism roller combinations, of which at least one is so mounted that it can be adjusted, each drawing mechanism roller combination consists of at least one driven lower roller and at least one upper roller (press roller) lying, in operation, on top of the lower roller and so mounted that it can be lifted off.  
     In order to allow optimisation of specific drawing mechanism settings using the same fibre material, with fibre slivers inserted,  
     a) the upper rollers are unloaded or lifted off,  
     b) the mountings of at least one lower roller are unlocked,  
     c) the mountings are adjusted to the desired nip line spacing using a displacement device,  
     d) the mountings are subsequently re-locked.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority of German Patent ApplicationNos. 102 42 388.1 filed Sep. 13, 2002 and 103 29 836.3 filed Jul. 2,2003, the subject matters of which are incorporated herein by reference.

[0002] The invention relates to a method, at a draw frame for fibreslivers, of adjusting the nip line spacing of a drawing mechanism, whichhas at least two drawing mechanism roller combinations, of which atleast one is so mounted that it can be adjusted, wherein each drawingmechanism roller combination consists of at least one driven lowerroller and at least one upper roller (press roller) lying on top of thelower roller and so mounted that it can be lifted off, and encompassesan apparatus for carrying out the method.

[0003] In practice, adjustment of the nip line spacings is carried outwithout fibre slivers in the drawing mechanism, that is to say the fibreslivers are drawn off from the drawing mechanism completely and,subsequently, the nip line spacings are adjusted. It is not possible, bythat means, to optimise existing drawing mechanism settings whilst usingthe same fibre material.

[0004] In a known apparatus (DE-OS 20 44 996), the mountings of theintake and middle lower rollers are displaceable on the frame of themachine so that the extent of the drawing zone can be matched to theparticular fibre staple. A tensioning pulley wheel, which isdisplaceable in a guideway in the frame of the machine, allows thelength of the toothed belt to be modified in accordance with the changedspacing between the axes of the middle roller and a guide pulley wheel,brought about by displacement of the intake roller. The middle roller isdriven by a further toothed belt. The latter toothed belt is tensionedby a tensioning pulley wheel which is fastened to the machine frame andwhich can pivot about one axis; as a result, it can also be matched tochanged spacings between the axes of the intake roller and middleroller. It is disadvantageous that displacing devices for displacementof the intake roller and the middle roller and additional tensioningdevices for re-tensioning of the toothed belts after the displacementoperations are necessary, requiring a considerable outlay in terms ofconstruction. In addition, it is disadvantageous that a number of worksteps are required for the displacement operations and the subsequentre-tensioning operations. The belt tension is destroyed by thedisplacement process. Where the displacement is carried out manually,spacers are inserted between the mountings, the mountings being pushedagainst the spacers so that, in this case too, the amount of set-up workis considerable. Finally, the displacement and re-tensioning operationsresult in a doubling of potential error sources when setting thespacings and belt tensions.

[0005] The problem underlying the invention is accordingly to provide amethod of the kind described at the beginning that avoids thedisadvantages mentioned and that especially allows optimation ofspecific drawing mechanism settings using the same fibre material.

[0006] The problem is solved by the characterising features of claims 1and 3.

[0007] The fact that adjustment of the nip line spacings is carried outwith fibre slivers inserted allows, in accordance with the invention,optimisation of specific machinery-related and/or fibre-related settingsof the drawing mechanism using the same fibre material. The optimumextent of the drawing zone is dependent on, amongst other things, thelength of fibres (staple length). It is likewise possible to determineand set an optimum drafting value.

[0008] The invention also encompasses an advantageous apparatus at adraw frame having a drawing mechanism for the doubling and drafting offibre slivers, having a drawing mechanism frame for accommodating thedrawing mechanism, which has at least two pairs of rollers eachcomprising an upper roller and a lower roller, having means foradjusting the spacing of at least one of the lower rollers in relationto another lower roller, in each case having a mounting foraccommodating the lower roller, wherein lower rollers are arranged to bedriven by at least one drive element endlessly revolving around pulleywheels, wherein at least one pulley wheel and the tensioned guideelement are used for adjusting a slider (mounting), wherein a movingforce applied to the pulley wheel or to the drive element can beconverted into the adjusting movement for the slider.

[0009] Claims 2, 4 to 9, and 11 to 67 contain advantageous developmentsof the invention.

[0010] The invention will be described hereinafter in greater detailwith reference to exemplary embodiments shown in the drawings, in which:

[0011]FIG. 1 shows, in a diagrammatic side view, an autoleveller drawframe for the apparatus according to the invention together with ageneral circuit diagram;

[0012]FIG. 2 shows the displaceable mounting of the intake and middlelower rollers;

[0013]FIGS. 3a and 3 b show the drive for the intake and middle lowerrollers for the draw frame according to FIG. 1, in a side view (FIG. 3a)and plan view (FIG. 3b);

[0014]FIGS. 4a to 4 d show, in diagrammatic form, the sequentialprocedure for shortening of the preliminary and main draft zones;

[0015]FIGS. 5a and 5 b show the intake and middle lower rollers beforedisplacement (FIG. 5a) and after displacement (FIG. 5b);

[0016]FIGS. 6a and 6 b show, in diagrammatic form, an electro-magneticbraking apparatus for a toothed belt wheel;

[0017]FIG. 7 shows a locking device for a slider;

[0018]FIG. 8 shows a connection element (bridge) for connecting twosliders;

[0019]FIG. 9 shows an embodiment comprising a drawing mechanism havingthree roller combinations, each having its own drive motor;

[0020]FIG. 10 shows input devices for manual and/or memory-assistedinput of adjustment values for changing the nip line spacings in thedrawing mechanism; and

[0021]FIG. 11 shows an upper roller lifted off from a lower roller.

[0022] In accordance with FIG. 1, a draw frame 1, for example aTrutzschler HSR draw frame, has a drawing mechanism 2, upstream of whichis an intake 3 of the drawing mechanism and downstream of which is anexit 4 from the drawing mechanism. The fibre slivers 5, coming from cans(not shown), enter the sliver guide 6 and, drawn by the draw-off rollers7, 8, are transported past the measuring element 9. The drawingmechanism 2 is designed as a 4-over-3 drawing mechanism, that is to sayit consists of three lower rollers I, II, III (I delivery lower roller,II middle lower roller, III intake lower roller) and four upper rollers11, 12, 13, 14. Drafting of the fibre sliver combination 5′ from aplurality of fibre slivers 5 is carried out in the drawing mechanism 2.Drafting is composed of preliminary drafting and main drafting. Theroller pairs 14/III and 13/II form the preliminary draft zone and theroller pairs 13/II and 11, 12/I form the main draft zone.

[0023] The attenuated fibre slivers 5 reach a web guide 10 in the exit 4from the drawing mechanism and, by means of the draw-off rollers 15, 16,are drawn through a sliver funnel 17, in which they are combined to formone fibre sliver 18, which is then deposited in cans. Reference letter Adenotes the work direction.

[0024] The draw-off rollers 7, 8, the intake lower roller III and themiddle lower roller II, which are connected to one another mechanically,for example by toothed belts, are driven by the control motor 19, itbeing possible, in the process, for a desired value to be specified.(The associated upper rollers 14 and 13, respectively, revolve by virtueof the motion of the lower rollers.) The delivery lower roller I and thedraw-off rollers 15, 16 are driven by the main motor 20. The controlmotor 19 and the main motor 20 each have their own controller 21 and 22,respectively. Control (speed-of-rotation control) is carried out in eachcase by means of a closed control loop, a tachogenerator 23 beingassociated with the control motor 19 and a tachogenerator 24 beingassociated with the main motor 20. At the intake 3 of the drawingmechanism, a variable proportional to the weight of the fibre slivers 5fed in, for example their cross-section, is measured by an intakemeasuring element 9 known, for example, from DE-A-44 04 326. At the exit4 from the drawing mechanism, the cross-section of the delivered fibresliver 18 is ascertained by an exit measuring element 25 associated withthe sliver funnel 17 and known, for example, from DE-A-195 37 983. Acentral computer unit 26 (control and regulation device), for example amicrocomputer with a microprocessor, sends a setting for the desiredvalue for the control motor 19 to the controller 21. The measurementvalues of the two measuring elements 9 and 25 are sent to the centralcomputer unit 26 during the drawing process. The desired value for thecontrol motor 19 is determined in the central computer unit 26 from themeasurement values of the intake measuring element 9 and from thedesired value for the cross-section of the delivered fibre sliver 18.The measurement values of the exit measuring element 25 are used formonitoring of the delivered fibre sliver 18 (delivered slivermonitoring). By means of this control system, it is possible forvariations in the cross-section of the fibre slivers 5 fed in to becompensated, and for the fibre sliver to be made more uniform, byappropriately regulating the drafting process. Reference numeral 27denotes a display monitor, 28 an interface, 29 an input device, 30 apressure rod and 31 a memory.

[0025] In accordance with FIG. 2, the trunnions Ia, IIa, IIIa (see FIG.3b) of the lower rollers I, II and III are mounted so as to be capableof rotation in mountings 32 a, 33 a, 34 a (32 b, 33 b, 34 b are locatedon the other side of the drawing mechanism and are not shown). Themountings 33 a and 34 a are bolted onto sliders 35 a and 36 a,respectively, which are displaceable in the direction of the arrows C, Dand E, F, respectively, along a bar 37 a. The two ends of the bar 37 aare fixedly mounted in mounting blocks 38′ (38″ not shown), which areattached to the frame 39 of the machine.

[0026] Displacement of the sliders 35 a, 35 b; 36 a, 36 b at the sametime causes the mountings 33 a, 33 b; 34 a, 34 b and, as a result, thelower rollers II and III, respectively, to be displaced and moved indirections C, D and E, F, respectively. The associated upper rollers 13and 14 are correspondingly moved (in a manner not shown) in directionsC, D and E, F, respectively. By that means, the nip line spacingsbetween the roller combinations are modified and set.

[0027] Locking of the sliders 35 a, 35 b; 36 a, 36 b is accomplished bymeans of a catch device, stopping device or the like (see FIG. 7).

[0028] In accordance with FIG. 3a, the lower rollers II and III aredriven from the right-hand side, seen in the direction of material flowA, by means of a common loop mechanism in the form of toothed beltwheels 40, 41 and a toothed belt 47. The different speeds of rotation ofthe lower rollers II and II are achieved by means of change-gearwheelsat the drive trunnions IIa, IIIa provided with different numbers ofteeth. The toothed belt 47 runs in direction B (that is to say contraryto the work direction) onto the control drive, which is in the form of aservo motor 19. The lower roller I is driven from the left-hand side ofthe machine by means of a loop mechanism in the form of toothed beltwheels and a toothed belt 47. For that purpose, the toothed belt 47′runs on the left-hand side from the toothed belt disc 40 at the lowerroller I in direction G onto the servo motor 20.

[0029] In operation, that is to say when the fibre slivers are runningin direction A, the toothed belt 47 moves in direction G. Starting fromthe toothed belt wheel 47 arranged on the drive motor 19, the toothedbelt 47 runs successively over a toothed belt wheel 45, a smooth guidepulley wheel 46, the toothed belt wheel 40 (roller-driving pulley wheelfor the lower roller III), the toothed belt wheel 41 (roller-drivingpulley wheel for the lower roller II), a smooth guide pulley wheel 42and a toothed belt wheel 43. By means of its teeth, the toothed belt 47is in positive engagement with the toothed belt wheels 40, 41, 43, 44and 45. The smooth side (reverse) of the toothed belt 47, opposite thetoothed side, is in contact and in engagement with the smooth guidepulley wheels 46 and 42. The toothed belt 47 loops around all the pulleywheels 40 to 46. In operation (when the fibre slivers are running indirection A during drafting), the toothed belt wheels 40, 41, 43, 44 and45 rotate clockwise and the guide pulley wheels 42 and 46 rotateanti-clockwise.

[0030] The toothed belt wheels 40, 41 are associated with the mountings34 a and 33 a, respectively, whereas the guide pulley wheels 42, 46 areattached to the sliders 35 a and 36 a, respectively, in a mannerallowing rotation. Because of the rigid attachment between the mounting34 a and the slider 36 a and between the mounting 33 a and the slider 35a (for example, by means of bolts), there are associated with the lowerrollers II and III, in each case, one toothed belt wheel 40 to 41 andone guide pulley wheel 46 and 42, respectively. The toothed belt 47 runsaround the pulley wheels 40, 46, on the one hand, and around the pulleywheels 41, pulley wheel 42, on the other hand, in a mirror-reflectedarrangement (see FIG. 3b).

[0031] The zone between the pairs of rollers 13/II and 14/III isdesignated VV (preliminary drafting) and the zone between the pairs ofrollers 12/I and 13/II is designated HV (main drafting) (see FIG. 4a).When, in accordance with FIG. 3a, the nip line spacing between theroller pairs 14/III and 13/II is to be increased, at least one pair ofrollers must be moved away from the respective other pair of rollers.For that purpose the slider 35 a may be displaced towards the right,which may be accomplished in two ways:

[0032] a) The slider 35 a is unlocked. A pulley wheel, for example thetoothed belt wheel 44, is stopped so that there is no possibility ofrotation. Stopping may be accomplished, for example, by mechanical orelectromagnetic means. As a result the toothed belt 47 is stationary andcannot be moved. The toothed belt wheel 41 is then rotatedanti-clockwise, for example manually using a crank or the like,whereupon the guide pulley wheel 42 likewise rotates, clockwise, as amatter of necessity. In the process, the rotary movement of the toothedbelt wheel 41 is converted into a longitudinal movement of the slider 35a in direction C, the toothed belt wheel 41 and the guide pulley wheel42 winding along opposite sides of the stationary toothed belt 47,thereby “shortening”, as it were, the toothed belt 47 at one pulleywheel and “lengthening” it at the other pulley wheel. The length of beltrequired during that “winding along” at the toothed belt wheel 41 ismade available at the guide pulley wheel 42. The lower roller II isthereby displaced in direction C by means of the slider 35 a and themounting 33 a.

[0033] b) The slider 35 a is unlocked. The toothed belt wheel 41 isstopped so that there is no possibility of rotation. As a result theguide pulley wheel 42 is also stopped of necessity. Then, clockwiserotation is brought about by means of the drive motor 19. The toothedbelt 47 moves in direction G, likewise “shortening” the belt 47 at onepulley wheel and “lengthening” it at the other pulley wheel. The lengthof belt actually required between the toothed belt wheels 40 and 41 ismade available between the toothed belt wheels 43 and 42. The rotarymovement of the toothed belt wheel 44 and the movement of the toothedbelt 47 is thereby converted into a longitudinal movement of the slider35 a in direction C. The lower roller II, mounted in the mounting 33 a(which is rigidly connected to the slider 35 a), is likewise moved indirection C as a result.

[0034] In practice, it is often the case that, in accordance with FIGS.4a to 4 d, first the preliminary draft zone VV is modified and then themain draft zone HV. In the case of shortening of the draft zones VV andHV, the slider 36 a is displaced in the direction of the arrow E fromthe position according to FIG. 4a into the position according to FIG.4b. As a result, the nip line spacing in the preliminary draft zone VVis reduced from “a” to “a′”. Then, in accordance with FIG. 4c, thesliders 36 a and 35 a are rigidly connected to one another by means of abridge 50. Finally, the rigidly coupled sliders 36 a and 35 a are moved,in accordance with FIG. 4d, in the direction of the arrows E and C, fromthe position shown in FIG. 4c into the position shown in FIG. 4d. As aresult, the nip line spacing in the main draft zone HV is shortened from“b” to “b′”.—A corresponding procedure is used in the case oflengthening the preliminary and main draft zones, that is to say thecoupled sliders 35 a and 36 a are displaced in the direction of thearrows F and D (see FIG. 2), as a result of which the main draft zone HVis lengthened. Then, the sliders 35 a and 36 a are uncoupled from thebridge 50. Finally, the slider 36 a is moved in the direction of thearrow F (see FIG. 2), as a result of which the preliminary draft zone VVis lengthened.

[0035] With regard to the fibre slivers 5 in the drawing mechanism 2, itshould be noted that, in the case of shortening of the draft zones VVand HV, a small amount of stretching, in direction B, of the fibreslivers 5″, upstream of the pair of rollers 14/III can occur ondisplacement in accordance with FIGS. 4a, 4 b, but because of the length(about 1.5 m) of the spacing between the transport rollers 7, 8 and thepair of rollers 14/III this is without significance. In the case ofshortening, a sagging loop does not form in the preliminary draft zoneVV because in the case of displacement referring to the pairs of rollers14/III and 13/111 either one or both pairs of rollers are rotatablebecause the drives to both pairs of rollers are coupled by way of thetoothed belt 47. In contrast, in the case of shortening of the maindraft zone HV, a sagging loop is formed in fibre slivers 5″, which isdrawn out or drawn straight by rotation of the pair of rollers 12/I inthe work direction A by means of the main motor 20.—In the case oflengthening of the draft zones VV and HV, the pair of rollers 12/I is,in a first step, rotated backwards in direction B, whereupon a saggingloop is intentionally formed in the fibre slivers 5″. When the maindraft zone HV is subsequently lengthened by displacement of the coupledsliders 35 a and 36 a in direction D and F, the artificially formed loopis, in the process, once again drawn out or drawn straight. Finally,after uncoupling of the bridge 50, the slider 36 a is displaced indirection F. As a result of the above-mentioned coupling of the drivesto the intake and middle lower roller pairs by means of the toothed belt47, the length of the fibre slivers 5′ in the preliminary draft zone VVremains unaffected. Possible slight compression of the fibre slivers 5^(IV) upstream of the pair of rollers 14/III is, in respect of thedrafting and the constitution of the fibre slivers 5 ^(IV), withoutsignificance.

[0036]FIGS. 5a, 5 b show the construction bringing about thedisplacement of the sliders 36 a and 35 a. The nip line spacing in thepreliminary draft zone VV is lengthened from “a” (FIG. 5a) to “a″” (FIG.5b). The sliders 36 a and 35 a are displaced one after the otheraccording to the arrows E and C, respectively. Displacement isaccomplished by stopping the toothed belt wheel 40 or fixing it with aholding brake or the like and then actuating the drive motor 19,whereupon the toothed belt 47 moves. In continuation thereof, thesliders 36 a and 35 a are displaced in accordance with FIGS. 4a, 4 band, subsequently, FIGS. 4c, 4 d.

[0037] In accordance with FIG. 6a, an electromagnetic holding brake isprovided, which has a rod-shaped iron core 53 surrounded by a plungercoil 54. Mounted on one end face of the iron core 53 is a brake shoe 55,for example made of plastics material or the like. The iron core 53 isdisplaceable in the direction of the arrows M, N. When current flowsthrough the plunger coil 54, the iron core 53 is moved in direction M,in accordance with FIG. 6b, so that the brake shoe 55 is pressed againstthe smooth cylindrical surface of the shaft 44 a of the toothed beltwheel 44. As a result, the toothed belt wheel 44 is fixed (stopped) sothat it cannot rotate, for as long as voltage is applied to the plungercoil 54.

[0038] In accordance with FIG. 7, a pneumatic cylinder 60 having apiston rod 61 is attached to the slider 36 a. When subjected to pressurefrom the pneumatic cylinder 60, the piston rod 61 is moved out in thedirection of the arrow P and comes to rest, with a high degree ofcontact pressure, against the machine frame 61. The slider 36 a is fixed(stopped) so that it cannot be displaced with respect to the bar 37 a,for as long as compressed air is applied to the pneumatic cylinder 60.

[0039] In accordance with FIG. 8, there is provided, as the bridge 50between the sliders 35 a and 36 a, a flat piece of metal (plate), whichis fastened in the region of one of its ends 50 a to the slider 36 a,for example using bolts. In its region 50 b facing the slider 35 a, theflat piece of metal has an elongate hole 50 c, through which a bolt 62can engage in a threaded hole (not shown) in the slider 35 a. By meansof this bridge 50, the sliders 35 a and 36 a can be rigidly connected toone another, releasably, at different spacings with respect to oneanother.

[0040] In accordance with FIG. 9, in contrast to FIG. 1, each lowerroller I, II and III is driven by its own drive motor 20, 52 and 19,respectively, as shown, for example, in DE-OS 38 01 880. The motor 20drives the toothed belt wheel 55 of the lower roller I by way of thetoothed belt 56; the motor 52 drives the toothed belt wheel 41 of thelower roller II by way of the toothed belt 57; and the motor 19 drivesthe toothed belt wheel 40 of the lower roller III by way of the toothedbelt 47. Attached to the slider 36 a, in addition to the smooth guidepulley wheel 46, is a further smooth guide pulley wheel 51. The endlesstoothed belt 47 loops around, in succession, the pulley wheels 44, 46,40, 51 and 43. The toothed belt wheels 44, 40 and 43 are in engagementwith the teeth of the toothed belt 47, whereas the smooth guide pulleywheels 46 and 51 are in engagement with the smooth reverse side of thetoothed belt 47. The sliders 35 a and 36 a are rigidly connected to oneanother, releasably, by means of the bridge 50. When they are notconnected by the bridge 50, the sliders 35 a and 36 a are individuallydisplaceable and when they are connected by the bridge 50 they arejointly displaceable.

[0041] In accordance with FIG. 10, the drive motor 19 for lower rollersII and III is in communication with the electronic control andregulation device 26. Adjustment values for modification of the draftzones VV and HV (that is to say the extents of the drawing zones) eithercan be entered manually by way of the input device 29 or can be calledup from a memory 31 for particular categories of fibre material.

[0042] Adjustment of the nip line spacing in the preliminary draft zoneVV and/or the main draft zone HV can be carried out with the fibreslivers 5 inserted.

[0043] Displacement can be carried out with the upper rollers 11 to 14in the loaded state. FIGS. 1 and 10 show inserted fibre slivers 5 andloaded upper rollers 11 to 14. With the fibre slivers inserted and theupper rollers 11 to 14 loaded, the sliders 35 a, 36 a or mountings of atleast one lower roller II, III are unlocked, the sliders or mountingsare set to the desired nip line spacing a, a′; b, b′ by means of adisplacement device, for example in accordance with FIGS. 3a, 3 b; 5 a,5 b and then the sliders 35 a, 36 a or mountings are locked again (forexample in accordance with FIG. 7).

[0044] Displacement can also be carried out with the upper rollers 11 to14 lifted off. The upper rollers 11 to 14 may be lifted off completelyfrom the lower rollers I to III in the manner shown in DE-OS 197 04 815,the upper roller 14 being swung out on a portal 58 about a pivotmounting 59. However, it may also be sufficient for the upper rollers 11to 14 to be unloaded and to be lifted off from the lower rollers I toIII only to a slight degree such that the fibre slivers 5 are not caughtby the pairs of rollers during displacement of the draft zones VV and HVbut can slide through the roller nip without being adversely affected.

[0045] The invention has been illustrated using the example of theadjustment of the nip line spacings of a drawing mechanism of a drawframe. It likewise encompasses the adjustment of drawing mechanisms ofother machines, for example carding machines, combing machines, flyframes and ring spinning frames.

1. Method, at a draw frame for fibre slivers, of adjusting the nip linespacing of a drawing mechanism, which has at least two drawing mechanismroller combinations, of which at least one is so mounted that it can beadjusted, wherein each drawing mechanism roller combination consists ofat least one driven lower roller and at least one upper roller (pressroller) lying, in operation, on top of the lower roller and so mountedthat it can be lifted off, characterised in that, with fibre sliversinserted, a) the upper rollers are unloaded or lifted off, b) themountings of at least one lower roller are unlocked, c) the mountingsare adjusted to the desired nip line spacing using a displacementdevice, d) the mountings are subsequently re-locked.
 2. Method accordingto claim 1, characterised in that the transport rollers are lifted off.3. Method, at a draw frame for fibre slivers, of adjusting the nip linespacing of a drawing mechanism, which has at least two drawing mechanismroller combinations, of which at least one is so mounted that it can beadjusted, wherein each drawing mechanism roller combination consists ofat least one driven lower roller and at least one upper roller (pressroller) lying on top of the lower roller and so mounted that it can belifted off, characterised in that, with fibre slivers inserted and upperrollers loaded, a) the mountings of at least one lower roller areunlocked, b) the mountings are adjusted to the desired nip line spacingusing a displacement device, c) the mountings are subsequentlyre-locked, a loop of fibre material formed in a draft zone being drawnstraight (evened out).
 4. Method according to claim 3, characterised inthat the preliminary or main draft zone spacing is reduced and,simultaneously or subsequently, the loop of fibre material in the maindraft zone is drawn straight (evened out).
 5. Method according to claim3, characterised in that the loop of fibre material is evened out byrotation of the delivery roller combination in the work direction (A).6. Method according to claim 3, characterised in that a loop of fibrematerial is formed in the main draft zone and, subsequently orsimultaneously, the preliminary or main draft zone spacing is increased.7. Method according to claim 3, characterised in that the loop of fibrematerial is formed by rotation of the delivery roller combinationcontrary to the work direction (B).
 8. Method according to claim 1,characterised in that the transport rollers are loaded.
 9. Methodaccording to claim 1, characterised in that, in the case of one drawingmechanism and a plurality of draft zones, adjustment of the nip linespacings is carried out in continuation from one draft zone to another.10. Apparatus at a draw frame having a drawing mechanism for thedoubling and drafting of fibre slivers, having a drawing mechanism framefor accommodating the drawing mechanism, which has at least two pairs ofrollers each comprising an upper roller and a lower roller, having meansfor adjusting the spacing of at least one of the lower rollers inrelation to another lower roller, in each case having a mounting devicefor accommodating the lower roller, wherein lower rollers are arrangedto be driven by at least one drive element endlessly revolving aroundpulley wheels, characterised in that at least one pulley wheel (40, 41,42, 43, 44, 45, 46; 51) and the tensioned drive element (47) are usedfor adjusting the mounting device (33 a, 33 b; 34 a, 34 b; 35 a, 35 b;36 a, 36 b), wherein a moving force applied to the pulley wheel (40, 41,42, 43, 44, 45, 46; 51) or to the drive element (47) can be convertedinto the adjusting movement for the mounting device (33 a, 33 b; 34 a,34 b; 35 a, 35 b; 36 a, 36 b).
 11. Apparatus according to claim 10,characterised in that the drive element is stationary and the pulleywheel is rotated.
 12. Apparatus according to claim 10, characterised inthat the pulley wheel is stationary and the drive element is moved. 13.Apparatus according to claim 10, characterised in that at least oneguide pulley wheel is attached to each slider (mounting); and theroller-driving pulley wheel or guide pulley wheel (s) act, in each caseone after the other, on both sides of the tensioned drive element. 14.Apparatus according to claim 10, characterised in that the rotation ofthe pulley wheel or the movement of the drive element is accomplishedmanually.
 15. Apparatus according to claim 10, characterised in that theslider is linearly displaceable.
 16. Apparatus according to claim 10,characterised in that the drive element is a toothed belt.
 17. Apparatusaccording to claim 10, characterised in that an endless flexible toothedbelt is present.
 18. Apparatus according to claim 10, characterised inthat the pulley wheels comprise toothed belt wheels.
 19. Apparatusaccording to claim 10, characterised in that the pulley wheels compriseguide pulley wheels.
 20. Apparatus according to claim 10, characterisedin that at least one driving pulley wheel is provided.
 21. Apparatusaccording to claim 10, characterised in that driven pulley wheels arepresent.
 22. Apparatus according to claim 10, characterised in that thedrive element loops around the pulley wheels.
 23. Apparatus according toclaim 10, characterised in that the drive element and the pulley wheelsare in engagement with one another.
 24. Apparatus according to claim 10,characterised in that the pulley wheel for adjustment of a slider is thedrive pulley wheel of a lower roller (roller-driving pulley wheel). 25.Apparatus according to claim 10, characterised in that the slider isdisplaceable during adjustment.
 26. Apparatus according to claim 10,characterised in that the slider is arranged to be stopped. 27.Apparatus according to claim 10, characterised in that the stoppingarrangement is releasable.
 28. Apparatus according to claim 10,characterised in that a display device for the position of the slider ispresent.
 29. Apparatus according to claim 10, characterised in that adrive motor is used for rotation of the pulley wheel.
 30. Apparatusaccording to claim 10, characterised in that a drive motor is used formovement of the drive element.
 31. Apparatus according to claim 10,characterised in that the drive motor is used for the lower rollers. 32.Apparatus according to claim 10, characterised in that a separate drivemotor is used.
 33. Apparatus according to claim 10, characterised inthat belt shortening or belt lengthening is arranged to be automaticallyevened out during adjustment.
 34. Apparatus according to claim 10,characterised in that the evening-out of belt length is carried out at aslider by two guide pulley wheels.
 35. Apparatus according to claim 10,characterised in that the lower rollers are arranged to be adjustedsingly and independently of one another.
 36. Apparatus according toclaim 10, characterised in that a roller-driving pulley wheel and aguide pulley wheel are attached to the slider of the intake roller and aroller-driving pulley wheel and a guide pulley wheel are attached to theslider of the middle roller.
 37. Apparatus according to claim 10,characterised in that the drive element runs around the pulley wheels atthe slider of the intake roller and around the pulley wheels at theslider of the middle roller in a mirror-reflected arrangement. 38.Apparatus according to claim 10, characterised in that the drive elementis in tension before, during and after the displacement.
 39. Apparatusaccording to claim 10, characterised in that the drive motor is incommunication with an electronic control and regulation device. 40.Apparatus according to claim 10, characterised in that a measuringelement is connected to the control and regulation device.
 41. Apparatusaccording to claim 10, characterised in that the measuring element iscapable of registering fibre-related and/or machinery-relatedmeasurement variables.
 42. Apparatus according to claim 10,characterised in that adjustment of the slider is carried out when thedraw frame is in operation.
 43. Apparatus according to claim 10,characterised in that adjustment of the slider is carried out when thedraw frame is not in operation.
 44. Apparatus according to claim 10,characterised in that adjustment of the slider is carried out duringcan-changing.
 45. Apparatus according to claim 10, characterised in thatthe draw frame is self-adjusting.
 46. Apparatus according to claim 10,characterised in that adjustment of the slider is carried out byinputting adjustment variables.
 47. Apparatus according to claim 10,characterised in that the adjustment variables can be input manually.48. Apparatus according to claim 10, characterised in that a memory foradjustment variables is connected to the control and regulation device.49. Apparatus according to claim 10, characterised in that the sliderfor the intake roller and the slider for the middle roller are arrangedto be connected by a rigid connecting element.
 50. Apparatus accordingto claim 10, characterised in that the connecting element is releasablyconnected.
 51. Apparatus according to claim 10, characterised in thatthe spacing of the pairs of rollers in relation to one another can beadjusted without fibre material.
 52. Apparatus according to claim 10,characterised in that the spacing of the pairs of rollers in relation toone another can be adjusted with fibre material.
 53. Apparatus accordingto claim 10, characterised in that the extent of the preliminary draftzone can be adjusted.
 54. Apparatus according to claim 10, characterisedin that the extent of the main draft zone can be adjusted.
 55. Apparatusaccording to claim 10, characterised in that the extent of thepreliminary draft zone and the extent of the main draft zone can beadjusted.
 56. Apparatus according to claim 10, characterised in thateach lower roller has its own associated drive motor.
 57. Apparatusaccording to claim 10, characterised in that the intake and middle lowerrollers are arranged to be driven by one drive motor.
 58. Apparatusaccording to claim 10, characterised in that a brake, stoppingarrangement or the like is associated with the stationary pulley wheel.59. Apparatus according to claim 10, characterised in that a mechanicalbrake, stopping arrangement or the like is present.
 60. Apparatusaccording to claim 10, characterised in that an electrical brake,stopping arrangement or the like is present.
 61. Apparatus according toclaim 10, characterised in that the drive motor is a self-braking motor.62. Apparatus according to claim 10, characterised in that anelectromagnetic brake, stopping arrangement or the like is present. 63.Apparatus according to claim 10, characterised in that the drive motordrives a further drive train, which has a free-wheel arrangement or thelike.
 64. Apparatus according to claim 10, characterised in that atleast three drawing mechanism roller combinations are present, of whichat least two are so mounted that they can be adjusted.
 65. Apparatusaccording to claim 10, characterised in that the mounting deviceconsists of the mounting (33 a, 33 b; 34 a, 34 b) and the slider (35 a,35 b, 36 a, 36 b).
 66. Apparatus according to claim 10, characterised inthat the mounting (33 a, 33 b, 34 a, 34 b) and the slider (35 a, 35 b,36 a, 36 b) are fastened to one another, for example by bolts. 67.Apparatus according to claim 10, characterised in that the mounting (33a, 33 b, 34, 34 b) and the slider (35 a, 35 b, 36 a, 36 b) are ofintegral construction.